In the case of traditional blood glucose level measurement, in order to collect blood, the body of the user has to be pierced with an instrument called a lancet at each measurement, which is problematic because it puts a heavy burden on the user and makes it impossible to perform continuous measurement.
In recent years, in order to eliminate such problems, a method has been proposed, in which blood glucose levels are measured in a continuous manner using CGM (Continuous Glucose Monitoring). In CGM, a sensor is partly deployed under the skin of the user and is used to measure the concentration of glucose in subcutaneous interstitial fluid (for example, see Patent Documents 1-3). While interstitial fluid is different from blood, the concentration of glucose in interstitial fluid matches the concentration of glucose in blood. Accordingly, a blood glucose level can be obtained by measuring the concentration of glucose in subcutaneous interstitial fluid. In addition, when CGM is used, the concentration of glucose in subcutaneous blood can also be measured directly through the deployed sensor.
Patent Documents 1-3 have disclosed a measuring apparatus used to measure glucose based on CGM. In addition, Patent Documents 1-3 have disclosed a method for deploying a sensor under the skin, as well as a device used in implementing said method. Here, the measuring apparatus disclosed in Patent Documents 1-3 will be described with reference to FIG. 18. FIG. 18 shows an example of a traditional measuring apparatus. In FIG. 18, the skin 104 is shown in cross-section.
As shown in FIG. 18, the measuring apparatus 100 includes a measurement unit 101, which has a sensor 103, and a receiving unit 105. Among these, the measurement unit 101 is placed on the surface of the user's skin 104. However, before the body of the measurement unit 101 is installed, a portion of the sensor 103 is embedded under the skin with the help of a dedicated piercing tool.
Specifically, the base portion 101a of the measurement unit 101 is first affixed to the surface of the user's skin 104 using adhesive tape 102. Next, a piercing tool (not shown), which has a sensor 103 installed therein, is attached to the base portion 101a. 
The piercing tool is configured to enable ejection of the sensor 103 along with a piercing needle (not shown) and the user or medical personnel ejects the sensor 103 by operating the piercing tool. The ejected sensor 103, along with the needle, pierces and becomes lodged in the user's skin 104. The needle is then retracted and only the sensor 103 remains deployed under the skin of the user. After that, the piercing tool is removed and the body portion 101b of the measurement unit 101 is attached on top of the base portion 101a. At such time, the body portion 101b and the sensor 103 are electrically connected.
In addition, while not shown in FIG. 18, glucose oxireductase is immobilized on the distal end portion of the sensor 103. The sensor 103 has a pair of electrodes extending from its proximal portion to the distal end, with one of these electrodes (working electrode) placed in contact with the glucose oxireductase on the distal end portion. Accordingly, when a voltage is applied between the two electrodes, electric current flows between the two electrodes in proportion to the concentration of the glucose contained in subcutaneous interstitial fluid, such that the concentration of glucose can be determined from the value of the current.
Furthermore, while not shown in FIG. 18, the proximal portion of the sensor 103 is connected to electrical circuitry contained inside the body portion 101b. When an electric current flows between the electrodes of the sensor 103, the electrical circuitry generates an analog signal identifying its value and, furthermore, converts this analog signal to a digital signal. The electrical circuitry then transmits the digital signal on a carrier wave to the receiving unit 105. In addition, the measurement unit 101 contains a power supply, power circuits, etc. The receiving unit 105 computes a specific glucose concentration based on the received digital signal and displays the computed value on its display.
Thus, the measuring apparatus 100 shown in FIG. 18 lightens the burden on the user because it does not require the body of the user to be pierced at each measurement. In addition, it enables continuous measurement because the concentration of glucose can be measured as long as the sensor 103 is deployed.